A former is known from DE 44 35 528 A1, which former has air outlet openings on its side and which former is acting together with a web. By arranging openings in a base plate and in a counter-plate, which counter-plate can be displaced in respect to the base plate, the effective air outlet openings can be varied from a maximum size, providing full coverage to zero, providing no coverage.
U.S. Pat. No. 5,423,468 A1 shows a guide element having an inner body with bores and with an outer body of a porous, air-permeable material. The bores in the inner body are only provided in the area which is expected to be engaged, or looped, by the web.
A sheet-conducting installation is known from DE 198 54 053 A1. Blown air flows through bores, slits, porous material or nozzles in a guide area of a guide element and in this way conducts the sheet in a contactless manner.
DE 29 21 757 A1 discloses a former, which has several compressed air supply chambers for blow-air openings in the area of its legs. Optimal air metering can be achieved by the position, size and shape of the openings.
The use of porous materials in the surface area of a spreading device in a paper-making machine is disclosed in EP 0 364 392 A2.
DE 295 01 537 U1 shows a sheet guide device. Air supply boxes with different configurations of air nozzles, with respect to size, arrangement and structure, for different requirements made on a holding or blowing force on the path of a web, are proposed.
A former disclosed in DE 100 31 814 A1 has blow-air openings in a leg, as well as in a nose area. A volume of the air flowing off underneath the web can be varied by locking element.
DE-A-11 42 878 also discloses a former with blow-air openings in a leg, as well as in a nose area. Here, the leg and nose areas can be charged with fluid at different pressures.